Multiple-stage centrifugal pump of inline design

ABSTRACT

The present invention relates to a multiple-stage centrifugal pump of inline design, comprising a connection housing ( 1 ) with connectors ( 2, 3 ) in the form of suction and pressure connectors, and a pump body ( 4 ). The pump body ( 4 ) is surrounded at a spacing by a casing tube ( 6 ) with the formation of a flow-guiding annular space ( 5 ). The pump body ( 4 ) and the casing tube ( 6 ) are fastened so as to transmit force between the connection housing ( 1 ) and a head piece ( 7 ), the head piece ( 7 ) is provided with a leadthrough for a motor-driven pump shaft ( 8 ), and the connection piece ( 1 ) is provided with a separating wall ( 9 ) which divides the suction and pressure regions, a flow-diverting guide element ( 10 ) being arranged in the transition region between the annular space ( 5 ) and a connector ( 3 ).

The invention relates to a multiple-stage centrifugal pump of inline design, comprising a connection housing with connectors in the form of suction and pressure connectors, a pump body, the pump body being surrounded at a spacing by a casing tube with the formation of a flow-guiding annular space, the pump body and the casing tube being fastened so as to transmit force between the connection housing and a head piece, the head piece being provided with a leadthrough for a motor-driven pump shaft, and the connection piece being provided with a separating wall which divides the suction and pressure regions.

A centrifugal pump of this type is known from DE 36 29 123 A1. A pump body which is equipped with a plurality of pump stages lies on its connection piece, rotors which are arranged in the said pump body being driven via a shaft by a motor which is arranged above a head piece. A pumping medium flows through the pump body in the direction of the head piece, in order to be deflected from this and, after exiting the pump body, radially to the outside into an annular gap. A perforated supporting ring centres the pump body in the head piece. A casing tube which surrounds the pump body at a spacing forms the annular gap. In the annular gap, the pumping medium flows back to the connection piece, is deflected in it and exits the connection body through a second connection.

Connection pieces of this type are configured as a cast construction or a multiple-part welded construction and have a separating wall, with the aid of which a division is made into suction and pressure region. The head pieces are also known as cast constructions or multiple-part welded constructions. A plurality of tie rods which are fastened to the connection piece and in the head piece and between which the pump body and the casing tube are clamped are usually required to hold the centrifugal pump together.

The invention is based on the object of improving the degree of efficiency of a centrifugal pump of this type. The first solution of this problem provides for a flow-diverting guide element to be arranged in the transition region between the annular space and a connector.

The guide element brings about a directed flow diversion from the annular channel into a connector. In the connection piece, this solution improves the overall flow guidance in this complex diversion and merging zone. This is because, in the connection piece, the homogenized annular-channel flow is deflected under very constricted spatial conditions and is merged in the connector cross section, usually the outlet or pressure connector, to form a full-surface-area flow cross section. With the aid of the guide element, a part flow of the annular-space flow, preferably that part flow which lies closest to the connector, is deflected here in the direction of an outlet flow in a manner which is favourable in flow terms. Eddies are therefore avoided and the overall degree of efficiency of a centrifugal pump of this type is improved considerably.

Refinements of the invention provide for the guide element to be arranged between the annular space and the pressure connector, for the guide element to be configured as a constituent part of the separating wall, or for the guide element to be connected by way of one or more rib-like elements to the separating wall and/or to a wall face of the connection piece, or for the guide element to be arranged as an insert part between the connection piece, pump body and/or casing tube and/or to be connected to it. The suitable fastening option for the guide element can therefore be selected as a function of a respectively used production type of a connection piece.

Other refinements of the invention provide for the guide element to be spatially curved and to have a trapezoidal or triangular contour in a projection onto the throughflow plane, or for the guide element to be of tab-shaped design, or for the guide element to protrude with its free end as far as up to or into the connector cross section, or for the guide element to be fastened by way of one end in the transition between the separating wall and the inner wall face of the annular space. These embodiments effectively facilitate the production and formation of a guide element of this type.

According to a further refinement of the invention, the tab-shaped guide element has a width in the region of an inner wall face of the annular space, which width is equal to or less than (=<) 0.75 times (x) the nominal width of the connector. The connection width of the guide element is preferably equal to or less than (=<) 0.5 times (x) the nominal width of the connector. Tests have shown that a very advantageous flow diversion is possible with this. Furthermore, there is provision for the flow diversion to form a flow channel which diverts by at least 75 degrees between a flow-diverting surface of the guide element and an opposite wall face of the annular space and/or connector. A part stream of the annular-space stream flows out of a flow channel of this type approximately tangentially into the connector cross section and/or a pipe which is connected to it. In the simplest way, negative effects of an annular-space flow which is directed perpendicularly with respect to the connector on the annular-space flow which is merged in the connection housing and is deflected and conducted away are prevented with the aid of the guide element.

A second solution of the problem provides for a flow-guiding annular element having a flow-guiding surface of convex design to bridge the space between an outflow opening of the pump body and an internal diameter at the inlet cross section of the annular gap. Eddies which are produced in the prior art by the flow transition from the pump body into the annular gap are successfully avoided within the flow with this. Baffles which transmit force and are provided with throughflow openings cause unnecessary throttling effects and eddies. In contrast, an undisrupted flow transfer is made possible by the convex formation of the flow-guiding surface of the annular element.

To this end, one refinement provides for an annular nozzle to be formed between the flow-guiding head-piece face and the annular element. As a result, additional influencing of the flow is possible, which flow exits from the last stage of the pump body and is diverted with low losses into the inlet cross section of the annular gap. To this end, the flow-guiding surface, which lies opposite the annular element, in the head piece has a concave design.

According to a further refinement, the annular element is connected by way of one or more guide elements to the head piece. The guide elements extend in the direction of the pump shaft and extend in the direction of the flow to be diverted. They therefore oppose the flow only with a minimum resistance. A further influencing of the flow and therefore an improvement in the degree of efficiency are possible as a result of a corresponding shape of the guide elements, as a function of the swirl directions which are situated within the flow and as a function of a respective design concept of the centrifugal pump. The head piece can be configured in one piece or multiple pieces and can be produced from a very wide variety of materials. This is dependent on a selected production process.

One exemplary embodiment of the invention is shown in the drawings and will be described in greater detail in the following text. In the figures:

FIG. 1 shows a centrifugal pump in part section, and

FIG. 2 shows a plan view of a connection piece, and

FIG. 3 shows a section through a head piece.

FIG. 1 shows a part section of a centrifugal pump of inline design, the connection housing 1 of which is provided with connectors 2, 3 in the form of suction and pressure connectors. Arrows show the flow direction within the connection housing 1. The connectors 2, 3 define the principal throughflow direction of the centrifugal pump and a pump body 4 is arranged perpendicularly with respect thereto, which pump body 4 is surrounded at a spacing by a casing tube 6 with formation of a flow-guiding annular space 5. A head piece 7 which is fastened above the pump body 4 serves to receive a drive motor. A pump shaft 8 is guided through the head piece 7, with the aid of which pump shaft 8 the individual rotors are driven within the pump body 4 of multiple-stage configuration. A separating wall 9 is situated within the connection piece 1, with the aid of which separating wall 9 the connection piece 1 is divided into a suction region and a pressure region.

A guide element 10 is integrated into the connection piece 1, which is configured here as a cast part, and is configured as a constituent part of the separating wall 9. In the case of a multiple-part configuration of the connection piece, for example in a segmented design with use of formed components, the guide element can also be integrated into another component or can be connected to it as a separate component.

A fluid flow which is conveyed by the pump part 4 is diverted in the head piece 7 and flows back to the connection piece 1 through the annular gap 5 which is formed by the casing tube 6. Since the flow direction in the annular gap stands perpendicularly on the inflow and outflow direction of the pump, a flow diversion takes place in the connection piece 1 along the separating wall 9 in the direction of the connector 3. Here, the flow is diverted by the guide element 10 in a manner which is favourable for flow and with low losses out of the annular-space region 5.1 which adjoins the connector 3, and is guided to the outlet cross section of the connector 3. The guide element 10 therefore prevents flows which cross totally or partially in the annular-space region 5.1. Instead, the annular-gap region 5.1 is shielded from the flow in the connection housing 1, as a result of which a substantial improvement in the degree of efficiency within the centrifugal pump is brought about. connection housing 1, as a result of which a substantial improvement in the degree of efficiency within the centrifugal pump is brought about.

FIG. 2 shows a plan view of the connection piece 1 in half section. The upper half of FIG. 2 exposes the view of the connection plane for the pump part 4. In the upper illustration of FIG. 2, the guide element 10 can be seen in the region of the connector 3, with the aid of which guide element 10 a flow diversion is effected out of the perpendicular downward direction into the horizontal direction from the annular space 5 to the connector 3 with the aid of the guide element 10. In this half section, the guide element 10 is drawn in plan view in the upper half in the annular-gap region 5.1 as a visible edge and is continued into the connector 3 as a dashed line. It can be seen from the projection onto the throughflow direction which is marked by the arrows that the guide element 10 is of tab-shaped design in this exemplary embodiment. In one embodiment of the connection housing in multiple-part form, for example as a sheet-metal part construction, the guide element 10 can be fastened with the aid of rib-like elements to the separating wall 9 and/or to a flow-diverting wall face 11 (cf. FIG. 1) of the connection piece 3. The lower half of FIG. 2 corresponds to a section through the centre line of the connectors 2, 3. The separating wall 9 is connected to the connector 2 in a fluid-tight manner and brings about the diversion of a fluid which is flowing into the connection piece 1 into the pump part 4 which stands perpendicularly on the centre line.

FIG. 3 is a detail from FIG. 1 and shows, in section, the final pump stage of the pump part 4 and the annular gap 5 which is formed by the casing tube 6. The end of the pump body 4 is covered by a flow-guiding annular element 12 which bridges between an outflow opening 13 of the pump body 4 and an internal diameter in the region of the inlet cross section 14 of the annular gap. Arrows show the throughflow direction within the head piece 7. Together with the annular element 12, a flow-guiding head-piece face 15 forms a type of annular nozzle for the flow to be diverted. A flow diversion with very low losses is therefore achieved. The annular element 12 is connected to the head piece 7 by way of one or more guide elements 16. Additional influencing of the flow to be diverted can be achieved with the aid of the guide elements 16 which are configured as a type of ribs or as flow fins. 

1. Multiple-stage centrifugal pump of inline design, comprising a connection housing (1) with connectors (2, 3) in the form of suction and pressure connectors, a pump body (4), the pump body (4) being surrounded at a spacing by a casing tube (6) with the formation of a flow-guiding annular space (5), the pump body (4) and the casing tube (6) being fastened to transmit force between the connection housing (1) and a head piece (7), the head piece (7) being provided with a leadthrough for a motor-driven pump shaft (8), and the connection piece (1) being provided with a separating wall (9) which divides the suction and pressure regions, wherein a flow-diverting guide element (10) is arranged in the transition region between the annular space (5) and a connector (3).
 2. Centrifugal pump according to claim 1, wherein the guide element (10) is arranged between the annular space (5) and the pressure connector.
 3. Centrifugal pump according to claim 1, wherein the guide element (10) is configured as a constituent part of the separating wall (9).
 4. Centrifugal pump according to claim 1, wherein the guide element (10) is connected by one or more rib-like elements to the separating wall (9) and/or to a wall face (11) of the connection piece (1).
 5. Centrifugal pump according to claim 1, wherein the guide element (10) is arranged as an insert part between the connection piece (1), pump body (4) and/or casing tube (6) and/or is connected to it.
 6. Centrifugal pump according to claim 1, wherein the guide element (10) is spatially curved and has a trapezoidal or triangular contour in a projection onto the throughflow plane.
 7. Centrifugal pump according to claim 1, wherein the guide element (10) is of tab-shaped design.
 8. Centrifugal pump claim 7, wherein the guide element (10) protrudes with its free end as far as up to or into the connector cross section.
 9. Centrifugal pump according to claim 7, wherein the guide element (10) is fastened by one end in the transition between the separating wall (9) and the inner wall face of the annular space.
 10. Centrifugal pump according to claim 1, wherein the tab-shaped guide element (10) has a width in the region of an inner wall face of the annular space, which width is equal to or less than (=<) 0.75 times (x) the nominal width of the connector (3).
 11. Centrifugal pump according to claim 1, wherein the connection width of the guide element (10) is equal to or less than (=<) 0.5 times (x) the nominal width of the connector (3).
 12. Centrifugal pump according to claim 1, wherein a flow channel which diverts by at least 75 degrees is formed between a flow-diverting surface of the guide element (10) and the opposite wall face of the annular space (5) and/or connector (3).
 13. Centrifugal pump claim 12, wherein a part stream of the annular-space stream flows out of the flow channel approximately tangentially into the connector cross section or a pipe which is connected to it.
 14. Centrifugal pump according to claim 1, wherein the flow-diverting surface of the guide element (10) is formed in two planes which lie perpendicularly with respect to one another and which are concave/planar or concave/convex and/or concave/concave.
 15. Multiple-stage centrifugal pump of inline design, comprising a connection housing (1) with connectors (2, 3) in the form of suction and pressure connectors, a pump body (4), the pump body (4) being surrounded at a spacing by a casing tube (6) with the formation of a flow-guiding annular space (5), the pump body (4) and the casing tube (6) being fastened to transmit force between the connection housing (1) and a head piece (7), the head piece (7) being provided with a leadthrough for a motor-driven pump shaft (8), and the connection piece (1) being provided with a separating wall (9) which divides the suction and pressure regions, wherein a flow-guiding annular element (12) having a flow-guiding surface of convex design bridges the space between an outflow opening (13) of the pump body (4) and an internal diameter (D_(i)) at the inlet cross section (14) of the annular gap.
 16. Centrifugal pump according to claim 15, wherein an annular nozzle is formed between the flow-guiding head-piece face (15) and the annular element (12).
 17. Centrifugal pump according to claim 15, wherein the annular element (12) is connected by one or more guide elements (16) to the head piece (7).
 18. Centrifugal pump according to claim 1, wherein the head piece (7) is configured in one piece or multiple pieces.
 19. Centrifugal pump according to claim 2, wherein the guide element (10) is arranged between the annular space (5) and the pressure connector.
 20. Centrifugal pump according to claim 16, wherein the annular element (12) is connected by one or more guide elements (16) to the head piece (7). 